Since transparent or translucent structures were first built, there has been a problem of how to shade the same during certain times of the day or certain seasons of the year. This is appliable whether a sun room, a passive solar structure, a solarium, various types of greenhouses, and the like.
Various types of coverings, slatted blinds, and other means have been tried over the years. In more recent times, mesh type screens have been developed, made of fiberglass and similar materials. These screens are often fixed along at least one edge and are stretched across the expanse of greenhouse area to be shaded. Light can filter through the screens and yet the desirable shading effect is accomplished. Until now, difficulties have invariably been encountered in having the screens lie juxtaposed to the translucent surface without wrinkling since wrinkling is very unattractive. Also when high wind conditions are encountered, flapping of the screens invariably occurs which is not only unattractive but is annoying and in some instances can actually be structurally damaging and endanger persons in the vicinity thereof.
In attempting to overcome the above-mentioned problems various hold down means have been used including cam type locks connected to the mullions and/or meeting rails of the structures. These efforts have proved unsuccessful in preventing wrinkling of the screens in static conditions and flapping of the screens in high wind conditions.